I like that idea, absorb some of the resonant energy present in the loaded rack, which is presumably vibrating.
On Wed, Sep 7, 2011 at 12:29 PM, Marc Schwartz <mschw...@nmsu.edu> wrote: > Dear Nicole &tc > > Perhaps cork or leather fender washers (as sold by Velo Orange, Rene Herse > (Boulder), and others) at the rack mounting bolts would provide sufficient > damping to deal with the shimmy, yet allow enough tightening torque on the > bolts to prevent them from working loose over time due to road vibrations. > > Fall comes to New Mexico; Smell the green chile a'roasting!!! > > Marc > ______________________________________ > > > On Sep 7, 5:33 pm, NME <nicolemea...@gmail.com> wrote: > > Thank you all for your really insightful comments! I tried a few more > > things, including some your suggestions -- made sure the wheels were > > aligned, checked tire pressure, etc. > > > > I noticed that the problem was much worse when I was on smooth > > asphalt, but would almost disappear when I was riding on gravel, > > cobblestones, or bricked sidewalk, so it occurred to me that the > > problem was this "harmonic" vibration -- not that the bike was out of > > alignment, but that it was too perfectly aligned. So on a whim, I > > *loosened* the bolts to the rack -- not enough that the rack wobbles > > or is in danger of coming unscrewed, but just enough that there can be > > some miniscule "give" between the rack and the frame. My idea was > > that if I could disrupt the perfect transmission of this vibration, > > then it wouldn't radiate to the front wheel, but would cancel itself > > out.dear > > > > It was the exact opposite of DougP's suggestion and the opposite of my > > original inclination, but it worked! It went from violent shimmy to > > completely smooth. No shaking at any speed. > > > > Is this perhaps another version of the "self-restoring force" Ken was > > talking about? (The maths are also beyond me.) In any case, if the > > problem happens again in another context, I'll be sure to look into > > "tire damping" (nice term) as a first resort! > > > > -- > > > > Thanks again, everyone! I'll finally be posting pictures of my AHH > > soon, now that I've got it properly scratched up and broken in. Five > > months in Berlin, and besides the daily commute, a few wonderful day > > rides already, and and now some inn-to-inn rides planned for fall. > > > > Nicole > > > > P.S. in answer to Ken's question -- neither me nor my mechanic are > > well-skilled. > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. > > > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. > > -- Ken Freeman Ann Arbor, MI USA -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
